In most video games, players typically control a character (e.g., an athlete, soldier, “rock-star,” superhero, monster, animal, imaginary creature or beast, etc.) or object (e.g., race car, spaceship, etc.) to perform various game actions in order to accomplish a game event.
In many multiplayer (and other) video games, players are often placed (or created) at a given location in a game map at the start of a gameplay session, or new level or round, etc. This process is known as “spawning.” “Respawning” is the replacement (or recreation) of a player at a given location in a game map during gameplay after he, she (or it) has been killed, destroyed, or otherwise removed from gameplay for a predetermined time period. Respawning is common in video games where a player may have multiple lives, such as in first-person shooter video games including, for example, the “Call of Duty®” video game franchise published by Activision Publishing, Inc. The locations in a game map at which players are spawned and/or respawned are known as “spawn locations” or “spawn points.”
Typically, potential spawn (and respawn) locations for a game map may be determined by video game designers. During game play, a computer system (e.g., a game server) that hosts a video game often determines an appropriate spawn location from among potential spawn locations for a player. Most players have an expectation that they will not be re-spawned during gameplay at a spawn location that puts them in immediate danger or harm's way. Otherwise, a player may be killed as she is re-spawned, or forced to engage opponents much more quickly than desired, leading to unsatisfactory gameplay. Indeed, the practice of “spawn camping,” or lying in wait at or near a spawn location in order to engage and/or kill opponents as they are being respawned, can be considered (depending on the game) poor sportsmanship.
Conventional attempts at identifying safe spawn locations at which to re-spawn players include direct line of sight computations from an enemy position and a spawn location to determine whether or not the spawn location is safe. However, such runtime computations can be computationally expensive because they typically involve issuing line of sight traces between a player position and the spawn location through the map geometry. Because of this computational burden, some computer systems may attempt to cache the most current information possible without simultaneously running multiple line of site calculations by performing a line of site computation each server frame, even if no spawn requests were made for that server frame. This can lead to outdated line of site information and slow down game processes (or prevent other game processes that could otherwise be performed) during the server frame.
Furthermore, conventional line of site determinations are error prone in many instances, and therefore fail to provide a good estimate of the relative safety of a given spawn location. For example, even though a given map node may not have a direct line of site to a spawn location, an enemy player at that map node may have to make only minimal movements to gain line of site to the spawn location, in which case the direct line of site test would not be a good indicator of the safety of the spawn location. For these and other reasons, it may not be possible to estimate the length of time a player might expect to live if re-spawned at a given spawn location using conventional direct line of site spawn systems.
These and other drawbacks exist with conventional spawning systems for video games.